Probing the Extragalactic Cosmic Rays origin with gamma-ray and neutrino backgrounds

Understand

GeV-TeV gamma-rays and PeV-EeV neutrino backgrounds provide a unique window on the nature of the ultra-high-energy cosmic-rays (UHECRs).

• We discuss the implications of the recent Fermi-LAT data regarding the extragalactic gamma-ray background (EGB) and related estimates of the contribution of point sources as well as IceCube neutrino data on the origin of the UHECRs.
• We calculate the diffuse flux of cosmogenic $\gamma$-rays and neutrinos produced by the UHECRs and derive constraints on the possible cosmological evolution of UHECR sources.
• In particular, we show that the mixed-composition scenario considered in \citet{Globus2015b}, which is in agreement with both (i) Auger measurements of the energy spectrum and composition up to the highest energies and (ii) the ankle-like feature in the light component detected by KASCADE-Grande, is compatible with both the Fermi-LAT measurements and with current IceCube limits.